/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.mpp.aggregation;

import org.apache.iotdb.db.mpp.execution.operator.window.IWindow;
import org.apache.iotdb.tsfile.file.metadata.enums.TSDataType;
import org.apache.iotdb.tsfile.file.metadata.statistics.Statistics;
import org.apache.iotdb.tsfile.read.common.block.column.Column;
import org.apache.iotdb.tsfile.read.common.block.column.ColumnBuilder;

import static com.google.common.base.Preconditions.checkArgument;

public class MaxTimeAccumulator implements Accumulator {

    protected long maxTime = Long.MIN_VALUE;
    protected boolean initResult = false;

    public MaxTimeAccumulator() {
    }

    // Column should be like: | ControlColumn | Time | Value |
    // Value is used to judge isNull()
    @Override
    public int addInput(Column[] column, IWindow curWindow) {
        int curPositionCount = column[0].getPositionCount();

        for (int i = 0; i < curPositionCount; i++) {
            // skip null value in control column
            if (column[0].isNull(i)) {
                continue;
            }
            if (!curWindow.satisfy(column[0], i)) {
                return i;
            }
            curWindow.mergeOnePoint();
            if (!column[2].isNull(i)) {
                updateMaxTime(column[1].getLong(i));
            }
        }
        return curPositionCount;
    }

    // partialResult should be like: | partialMaxTimeValue |
    @Override
    public void addIntermediate(Column[] partialResult) {
        checkArgument(partialResult.length == 1, "partialResult of MaxTime should be 1");
        if (partialResult[0].isNull(0)) {
            return;
        }
        updateMaxTime(partialResult[0].getLong(0));
    }

    @Override
    public void addStatistics(Statistics statistics) {
        if (statistics == null) {
            return;
        }
        updateMaxTime(statistics.getEndTime());
    }

    // finalResult should be single column, like: | finalMaxTime |
    @Override
    public void setFinal(Column finalResult) {
        if (finalResult.isNull(0)) {
            return;
        }
        initResult = true;
        maxTime = finalResult.getLong(0);
    }

    // columnBuilder should be single in maxTimeAccumulator
    @Override
    public void outputIntermediate(ColumnBuilder[] columnBuilders) {
        checkArgument(columnBuilders.length == 1, "partialResult of MaxTime should be 1");
        if (!initResult) {
            columnBuilders[0].appendNull();
        } else {
            columnBuilders[0].writeLong(maxTime);
        }
    }

    @Override
    public void outputFinal(ColumnBuilder columnBuilder) {
        if (!initResult) {
            columnBuilder.appendNull();
        } else {
            columnBuilder.writeLong(maxTime);
        }
    }

    @Override
    public void reset() {
        initResult = false;
        this.maxTime = Long.MIN_VALUE;
    }

    @Override
    public boolean hasFinalResult() {
        return false;
    }

    @Override
    public TSDataType[] getIntermediateType() {
        return new TSDataType[]{TSDataType.INT64};
    }

    @Override
    public TSDataType getFinalType() {
        return TSDataType.INT64;
    }

    protected void updateMaxTime(long curTime) {
        initResult = true;
        maxTime = Math.max(maxTime, curTime);
    }
}
